I. Field of the Invention
This invention relates generally to inspecting fiber optic connector endfaces using video microscopes. More specifically, the invention relates to an all-in-one fiber optic connector endface inspector that can rapidly complete entire inspection process without needing a display monitoring and locating the optical system of the microscope to the focused position for the connector endface.
II. Background
It is important in any fiber optic communication system that every optical fiber connector used in the system be inspected and cleaned prior to mating. Various types of hand-held video microscopes for inspecting connector endfaces have been produced over a decade. A typical hand-held inspector set consists of a microscope probe and a display unit connected through a cable. By monitoring the video image of the fiber endface on the display screen, the operator can adjust the focusing knob on the microscope probe to find the focused position for the fiber endface. A focused image can be captured and stored in the display; then, the display (often possessing a CPU inside) may conduct further ‘intelligent’ tasks, such as locating the fiber position in the image, indicating its ABCD zones (see ABCD-zone definitions in the international standard IEC 61300-3-35), and finally making its endface pass/fail judgment (based on the IEC 61300-3-35 criteria).
The U.S. Patent Application Publication by Huang et al, US20140327756 A1, provides a wireless microscope inspector in which the microscope probe wirelessly transmits video streaming in real-time to the target display through Wi-Fi. Eliminating the wire/cable between the microscope probe and the display allows more user-friendly operations. Another very important advantage of the wireless inspection lies in its wider display compatibility. In a wired approach, the display must have a port that matches the probe-specific cable plug and the display's operating system must work with the probe-specific communication protocol. But in a wireless case, any display device with Wi-Fi client functionality can receive the video signals from the wireless probe. The wide choices of displays include iOS devices (iPhone, iPad, and iPod), Android tablets, smart phones, smart TVs, PCs or special testing devices, etc. Yet, strictly speaking, such display compatibility is still not fully satisfactory. Since the ‘intelligent’ tasks mentioned above are conducted inside the display, different kinds of display operating systems (e.g. iOS versus Android) would require different application software designs. Even for different revisions of each kind of OS, the software could also be different.
To completely eliminate the display compatibility concerns, a useful solution is to include a microprocessor in the microscope probe so that the microscope probe itself can complete all the ‘intelligent’ tasks on the spot. In this case, the only functions of a display would be just receiving (via Wi-Fi) and showing: (a) the fiber endface images (for operators to monitor their focusing process) and (b) the final analysis reports. No more specific calculation software is needed in the display then.
Further, if the focusing of the fiber endface can be automatically done without monitoring and also the Pass/Fail result can be directly indicated on the probe (e.g. through a green/red LED), a display unit would virtually become unnecessary. Levin et al proposed such a probe in their U.S. Pat. No. 9,217,688 B2. In that patent, two software-controlled autofocusing approaches were proposed, either by moving the lens position or by adjusting the shape of a liquid lens. But in order to drive the lens movement or drive the liquid lens shape change, a motor with a controller or an electronic voltage controller must be built in the probe. With these extra components and functions, the probe's internal structure becomes rather complicated. Moreover, due to the extra power consumption (meaning a more powerful battery), the whole probe ends up fairly bulky and heavy.
Another concern about this autofocus approach is that the back-and-forth searching process for the optics of the microscope probe to locate the best focus position requires a steady handling of the probe. When inspecting a female connector, if the operator's hand is not stable enough, the time to settle the optics at the focused position could take tens of seconds.
Thus there is a need for a compact, lightweight, smart all-in-one probe, which can efficiently perform fiber connector enface inspection without a back-and-forth focusing process and independently of any display for an operator to monitor the process.